Jack DeWolf

Anyone have any insight as to an '86 930 just rebuilt that dies when oxygen sensor connected yet runs more or less without it? Hard to start, coughs a lot, minor backfires when cold. I must play with throttle extensively to keep it running then, once warm, is better at idle although it varies a lot (300 rpm to 1200 no pattern of variation detected so far). Despite all this it runs strong at normal speed. Any help/ideas much appreciated. The fuel accumulator holds pressure well. Wrench feels it may be a failing fuel distributor..Any experiences?

Bill Gregory

Jack,

I'm not too familiar with 930's, but the 86 turbo does use CIS fuel injection, which I have some familiarity with. Your symptoms sound like a vacuum leak(s)causing a lean condition. Are you sure all hoses and connections after the airflow sensor are on tight? You can use propane to locate a vacuum leak - the engine will gain rpm when propane hits the vacuum leak. A failing auxiliary air regulator can cause a slow and rough idle, however, that would clear up once the engine warms up.

A problem in the fuel supply could contribute to these symptoms. I'd want to check system fuel pressures, using a CIS pressure gauge. IF they were OK, I'd then want to check for fuel volume (each injector in a container, run fuel pump for 30 seconds, measure output. Looking for no more than 10% variance).

When you disconnect the O2 sensor, the engine will run slightly rich, which would tend to offset a lean condition. I'd investigate vacuum leaks first. If the fuel distributor was failing, I'd expect similar ill characteristics with or without the O2 sensor hooked up.

Pablo Naranjo

hi friend, im having problems at idle with an1977 930 turbo, i has already tested the auxiliary air regulator and the warm up regulator too many times, i had a vacuum leak but i already solve it, the engine works pretty fine when it gets hotter but in cold the engine does not acelerate even if i press the throttle all the way down

Pablo Naranjo

the probem its that when i open the idle mixture the car its on 2,000rmp but if i close it until the engine works correctly the engine has problems when runnning cold